## Abstract

The change of oxygen potential, ΔḠ_{o2}, for the solid solutions of general formula A_{y}^{2-}B_{z}^{3+}U_{1-y-z}O _{2+x} was studied by the method of configurational entropy calculation for cations and cation complexes. A part of Mg atoms (fraction m) were assumed to occupy the interstitial 4b sites of the solid solution, and the number of ways of arranging the free ions and intra-cation complexes was calculated followed by differentiation of the logarithm of this number with respect to oxygen non-stoichiometry to obtain partial molar entropy of oxygen. As the complexes, (A^{2+}U^{5+}), (A^{2+}2U^{5+}) and (B^{3+}U^{5+}) were assumed to be formed. For the first two complexes, an average composition (A^{2+}αU^{5+}) was defined, and for (B^{3+}U^{5+}) a fraction, β, of B^{3+} was considered to form the complex. The O/M ratio (M = A + B + U) which gave the steepest change of ΔḠ_{o2} was calculated. Below this O/M ratio to 2 - y - (1 - β)z/2, the solid solution possibly satisfied the relation m -X/(2y), where X = -x. In the region where this relation held, the solid solution was supposed to be oxygen stoichiometric.

Original language | English |
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Pages (from-to) | 232-238 |

Number of pages | 7 |

Journal | Journal of Nuclear Materials |

Volume | 282 |

Issue number | 2-3 |

DOIs | |

Publication status | Published - 2000 Jan 1 |

## ASJC Scopus subject areas

- Nuclear and High Energy Physics
- Materials Science(all)
- Nuclear Energy and Engineering